Glutamate sensitivity is a controversial topic that has proponents on both sides of the issue. Some researchers and a large number of alternative medicine practitioners believe there is a danger associated with sensitivity to this amino acid. On the other hand, there are a significant number of researchers and conventional medicine practitioners who point to studies that show this sensitivity to be relatively rare.

However, for those who are affected by sensitivity to this ingredient in many foods, more information is needed for them to safeguard their health better.

What Is Glutamate and Why Is it Important?

Glutamate is an amino acid and one of the most plentiful neurotransmitters in the brain. It is present only in small amounts, and it is the primary excitatory neurotransmitter. This means it stimulates neurons in the brain to transmit the chemical-electrical messages. It helps us talk, process information, think, learn new things, store new learning, and pay attention.

Some studies have indicated the more receptors for glutamate you have, the more intelligent you are. Large numbers of these receptors make it easier for you to learn and remember information. Unfortunately, these large numbers also make you at higher risk for stroke and seizures.

Glutamate and glutamic acid are essentially the same compound. Glutamate is the most common form of glutamic acid in the body. Glutamic acid is necessary for our bodies to function appropriately. It’s found in large quantities in both plant and animal protein, but we don’t necessarily have to eat this essential nutrient. Our bodies make it.

Glutamate is what is called an excitatory neurotransmitter. It works much like a stimulant, like coffee. Too much of it can lead to problems, but too little of it is also not good.

With too little glutamate, we would not be able to respond quickly to stimulation coming into our brain. Learning would be much more difficult, we wouldn’t be able to remember things very well, and we would have difficulty paying attention to information.

Too much glutamate can lead to excitotoxicity which can destroy neurons. Since glutamate is a stimulant to neurons, too much of it could cause these neurons to be overactivated and die.

Elevated levels of glutamate have also been linked to increased risk of seizures. Some researchers have also linked high levels of glutamate to the “wired but tired” experience people with Adrenal Fatigue Syndrome (AFS) report.

The same mechanism appears to be behind the “wired and tired” sensation and increased seizure risk. The increase in glutamate leads neurons to be overstimulated and become overly sensitive to stimuli of all kinds. The neurons fire when they don’t need to. All stimuli, light, sound, movement, and pain are amplified in the presence of increased glutamate. This brings on a condition of excitatory toxicity in the neurons and a shift toward seizures, resulting in the “wired and tired” feeling common in the early stages of AFS.

Bound and Free Glutamates

The two forms of glutamates, bound and free, are significantly different. The bound form of glutamate is that found in a complete protein source. It is typically digested and absorbed slowly. There is seldom any sensitivity to glutamate in this form.

However, glutamate sensitivity is much more common in free form. Free glutamates are not tied to other amino acids and are absorbed into your system much more quickly. This fast absorption rate leads to spikes in glutamate levels in your blood.

Some natural food sources contain free glutamate, but one of the most problematic sources is in processed and packaged food. Glutamate in the form of monosodium glutamate (MSG) is used as a preservative and flavor enhancer in these products.

MSG has been used for many years to flavor foods, especially soup, chips, and some types of Asian food. Some people who eat a lot of these foods develop symptoms after eating. In the manufacturing area, the processes used also tend to add contaminants to the foods as well.

Most sensitivities to glutamate are due to sensitivity to MSG. Many individuals also react to the associated contaminants found in processed foods.

These symptoms of sensitivity to glutamate or MSG are a source of controversy in the scientific arena. Some studies have found no connection between consuming foods with MSG and any of the above symptoms. However, many of these studies are funded by some component of the food industry. This brings into question the robustness of the findings. Many other sources of research have indicated a definite connection between these symptoms and consumption of products with MSG.

MSG and Glutamate Research

Recent research into the effects of high levels of glutamate/MSG has shown how damaging these compounds can become. For years, people have reported physical reactions to MSG, but research had not substantiated a connection. It does now appear that consuming MSG can lead to some significant health issues.

Research published in 2016 revealed any amount of MSG to be genotoxic. This means it damages cells, genetic material, and human lymphocytes, which are a type of white blood cell.

In 2015, research was published that showed kidney damage in animals who were fed MSG on a continuing basis.

Research from 2014 showed depressive behavior in animals due to chronic MSG consumption. Apparently, the MSG led to changes in levels of serotonin, a neurotransmitter affecting mood and emotions.

Another 2014 study showed a connection between MSG and allergy reactions. This study used a small sample of people who tended to have chronic hives.

In spite of these findings, the U.S. Food and Drug Administration in 1995 placed MSG in the same “generally regarded as safe” category as common condiments such as salt and pepper. A review published in 2009 in Clinical & Experimental Allergy supported this conclusion.

However, the genotoxicity of MSG has been shown in some significant research. MSG was shown to significantly increase the likelihood of chromosome aberrations, sister-chromatid exchanges, and cytokinesis-blocked micronucleus. Another part of this research also indicated MSG to lead to DNA damage in human lymphocytes.

Animal studies have consistently shown MSG to be toxic to several organ systems. The liver, brain, thymus, and kidneys have been detrimentally affected by MSG consumption in these studies. Chronic consumptions of MSG has been linked to renal fibrosis and oxidative stress, which is a major contributor to kidney damage.

Chronic ingestion of MSG leads to significantly increased metabolism of glutamate by the kidneys. This condition then leads to the production of reactive oxygen species (ROS). ROS, along with oxygen radicals, are a major part of free radicals in cells. When free radicals increase, due either to increased production or decreased elimination, oxidative stress occurs, increasing the risk of kidney damage.

The kidneys of rats exposed to MSG on an ongoing basis have shown decreased antioxidant levels and increased lipid peroxidation. With increased lipid peroxidation, the risk of kidney cancer increases. Lipids in the kidneys contain large amounts of long-chain polyunsaturated fatty acids. These fatty acids make the kidneys vulnerable to damage from ROS. Because of this, lipid peroxidation and protein modification, and therefore MSG, can also cause kidney damage.

Research has also suggested that MSG is strongly involved in neurological disorders. Autism, ALS, Parkinson’s, migraines, schizophrenia, Tourette’s, PANDAS, fibromyalgia, increased risk of stroke, and MS have all been linked to glutamate sensitivity. Other health conditions such as atrial fibrillation, insomnia, hyperactivity, OCD, and anxiety disorders, among others, have also been found to have a connection with glutamate.

Dangers of an Overabundance of Glutamate

Eosinophils (a type of white blood cells) can be increased with high levels of glutamate. This may lead to inflammation, and it can also hinder blood vessels, leading to migraines. Functioning of brain structures can also be detrimentally affected. These structures include the hypothalamus, hippocampal neurons, and Purkinje neurons, which can affect speech and language.

Glutamate has also been implicated in self-stimulating behaviors like rocking, body spinning, hand flapping, echolalia, and other repetitive body movements, as is commonly seen in children with autism.

With high levels of glutamate, mercury also becomes more toxic in the body. Cancer cells and tumors grow in the presence of high levels of glutamate.

When levels of glutamate increase, the brain releases natural opioids to prevent damage to the brain. This can lead to feelings of things not being quite right. It also depletes the brain’s supply of opioids and glutathione. Glutathione is necessary for detoxification, fighting inflammation, and gut health. It also aids in protecting neurons, so when the level of glutathione is low, more cell death occurs.

The gut microbiome becomes imbalanced by an increase in unhealthy bacteria with high levels of glutamate. The neurotransmitter acetylcholine is also increased in the presence of high levels of glutamate. This causes more stimulation in your nervous system, leading to feelings of anxiety and fear, difficulty sleeping, restlessness, and nervousness.

Sound double-blind scientific studies have been conducted to study the effects of MSG. In this research, neither the researcher nor the subjects are aware of which set of subjects is getting the target compound and which is getting a placebo, ensuring that bias and expectations don’t affect the results. These studies have shown that people who are sensitive to MSG can experience numbness, tingling, fatigue, and muscle tightness.

Sometimes people won’t react to ingestion of MSG right away. But its effects build up over time. Once these people reach what is called the “threshold of sensitivity,” symptoms begin to show.

What appears to happen in these cases is the MSG excites neurons at a low level initially. These stimulated neurons give rise to other neurons that are more sensitive to MSG. These overly-sensitive neurons eventually respond, leading to the MSG-sensitivity symptoms mentioned previously. The more of these neurons you have, the more likely you will experience glutamate sensitivity.

Dr. Lam’s Key Question

Why is glutamate sensitivity important to your health?

Glutamate sensitivity has been linked to several significant illness conditions. Parkinson’s Disease, ALS, migraines, MS, and fibromyalgia have been shown through research to be associated with this sensitivity. Glutamate is often found in the form of MSG, a commonly-used substance that enhances the flavor of foods, and it is hidden in many other ingredients.